OVERLOAD PREVENTION DEVICE FOR CONSTRUCTION MACHINE

摘要

An overload prevention device for a construction machine, preventing occurrence of engine lag down in a sharp rise of discharge pressure of a hydraulic pump to prevent the amount of fuel injection of an internal combustion engine from increasing sharply, thereby reducing fuel consumption in the entire work of the construction machine and improving operability of a hydraulic actuator etc. The overload prevention device has operating condition detection means and control means. The operating condition detection means detects operating conditions of an operation lever. When the control means determines, based on the operating conditions detected by the operating condition detection means, that the lever is operated at a speed higher than a predetermined speed, the control means outputs to discharge amount control means a control signal for setting input torque of a hydraulic pump at a minimum torque value in constant-torque control, and after that, the control means changes the level of the control signal according to a predetermined control pattern to increase the input torque of the hydraulic pump to a maximum torque value in the constant-torque control.